Column for contacting gaseous and liquid mediums have been known for decades. In certain cases empty vertical columns were used, in which the liquid was poured down on the internal mantle surface or was sprayed into the column, thus bringing about the contact with the upflowing gas. Naturally the effectiveness of this method was very low.
At the present time plate or packed towers are used for chemical and industrial distillation purposes.
The plate-type towers can be of two main groups, as follows: counterflow (shower) plate-and crossflow (overflow) plate columns.
An advantage of the plate columns is that there are practically no difficulties in connection with the liquid and gas distribution; on the other hand their drawback is the high specific pressure loss, involving high energy consumption. In addition their loadability and flexibility (adaptation to varying operating conditions) are limited.
Small-size packing bodies independent from each other are generally used as a packing for the packed towers; the packing of such towers have also recently been in the form of inserts made of mesh tissue.
The packings of mesh tissue consist of small cross sectional channels made of such material, placed vertically in the tower; the packing can also use a contacting device made of mesh tissue panels crossing each other at an angle filling out the interior of the tower.
The column packing of such packing bodies is formed mostly by a loose, irregular mass of such bodies, but packings of regular packing bodies too are known; in this case the packing bodies are in a regular geometrical arrangement in the column.
The presently known and used packing bodies differ from each other mainly with respect to their shape, the purpose of all the packing varieties being identical: placing mainly large-size bodies into the column, a uniform cavity formation should be realized, ensuring large voids volume, and sufficiently large specific contact surface by the use of inexpensive packing bodies which give a compact apparatus (small equipment dimensions at high effectiveness).
Since a uniform liquid and gas distribution cannot be properly ensured in presently known packed columns, ineffective slack spaces (dead area) or zones barely participating in the necessary phase-contact develop within the packing aggregate. The packings are very sensitive to solid (floating) impurities, clog easily, and cleaning is very complicated. These factors limit the applicability of the packed columns to a certain degree. Packings built up in a regular shape from packing bodies, can be generally used only in certain special technical fields (e.g. at vacuum distillation).
Effectiveness (volume) of the lattice works used in conventional cooling towers is relatively low, the volume to be built in is specifically very large.
The introduction of oxygen into water, waste water purification, or generally in the field of water treatment is an important task. For this purpose the oxygen is generally bubbled through the water, and/or the surface layers of the water are mixed or atomized with mechanical agitator (rotor), whereby the surface area of the water is increased and induction of the oxygen from the air is facilitated. The effectiveness of these methods is very low and the procedures are expensive; however their application in water treatment is indispensable.
Summing up, it can be stated, that at the present time there is contacting equipment known, which would be able to ensure effectively the contact of the two phases--gas (vapour) and liquid--in case of low phase flow at acceptable production and operation cost.